This application is based on Application Ser. Nos. 2001001625 and 2001192526, filed in Japan on Jan. 9, 2001 and Jun. 26, 2001, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a once-through pump (e.g., once-through blower) which is adapted to be incorporated in a domestic air conditioner, an automotive air conditioner, etc., for accelerating fluid in a flow passage while passing therethrough, and more specifically, it relates to a once-through pump which is capable of improving the pumping (or air-blowing) efficiency to thereby reduce noise in operation and achieve a sufficient pumping flow rate as well even within a limited design space.
2. Description of the Related Art
FIG. 25 is a cross sectional side view schematically illustrating a known once-through pump such as, for example, a once-through blower.
FIG. 26 is an enlarged cross sectional view illustrating the operation of fluid F in the vicinity of an impeller 100 in FIG. 25.
In FIG. 25, a heat exchanger 1 of an air conditioner is arranged on the upstream side of a flow passage P such as a channel, duct, etc., through which the fluid F such as air (see an arrow) passes.
The impeller 100 of a cylindrical shape, which constitutes the main body of the once-through blower, is integrally formed of a resin or the like, and is rotatably supported within the flow passage P.
The impeller 100 is driven to rotate around a rotation shaft or drive shaft 200 by the driving force of an unillustrated motor in a direction of arrow B.
The impeller 100 is provided on the outer periphery thereof with a multitude of vanes 101 (an array of vanes) at equal intervals in a symmetric relation with respect to the drive shaft 200.
Moreover, a tongue portion 2 is formed on the inner wall of the flow passage P for providing a cutoff structure, so that a portion of the flow passage P on the outer periphery of the impeller 100 is made into a bent or curved configuration about the tongue portion 2.
As a result, the fluid F in the impeller 100 generates a swirl or vortex E (see a clockwise arrow in FIG. 26) at a part near the tip of the tongue portion 2, as illustrated in FIG. 26, whereby the fluid F is accelerated while passing between adjacent ones of the rotating vanes 101.
That is, the fluid F located on the upstream side of the impeller 100 is sucked into the impeller 100 under a negative pressure of the vortex E, and discharged toward the downstream side of the impeller 100 while being accelerated by the centrifugal force of the impeller 100 acting in a rotational direction B.
In general, the once-through blower comprising the impeller 100 illustrated in FIG. 25 and FIG. 26 has a merit in that the amount of blast or air flow (i.e., flow rate) can be arbitrarily set by variably designing the size or dimensions of the flow passage P in a thrust direction of the drive shaft 200.
However, the condition of generation of the vortex E becomes unstable when some load is applied to a forward end (i.e., upstream side) or a rear end (i.e., downstream side) of the impeller 100 in practical use, thus making the blast or air-blowing function thereof unstabilized. As a result, the blower can only accommodate at most about 5 mmAq (50 Pa) as its tolerance to load.
In addition, noise generated by the vanes 101 would become violent under the influence of a negative pressure generated by the vanes 101 passing by the neighborhood of the vortex E.
With the known once-through blower (once-through pump) as described above, the tongue portion 2 is provided on the inner wall of the flow passage P at a location at which the impeller 100 is mounted so as to form the cutoff structure of the bent or curved configuration inside the flow passage P, so that a swirl or vortex E is thereby generated in the impeller 100, thus accelerating the fluid F in the flow passage P. As a consequence, there arise the following problems: the acceleration performance of the blower is unstable and the acceleration efficiency thereof is low; it is easy to generate noise; and it is impossible to generate a sufficient amount of blast or air flow within a limited design space.
The present invention is intended to obviate the various problems as referred to above, and has for its object to provide a once-through pump which is improved in its pumping efficiency, thereby making it possible to reduce noise and achieve a sufficient amount of pumping fluid or flow rate even within a limited space as designed.
Bearing the above object in mind, according to a first aspect of the present invention, there is provided a once-th rough pump for accelerating fluid in a flow passage while passing the fluid through the flow passage, the pump comprising: a cylindrical impeller rotatably supported in the flow passage; a plurality of vanes provided on the outer periphery of the impeller; a drive shaft for driving the impeller to rotate; wherein the impeller has a substantially D-shaped cross sectional configuration with a suction side, at which the fluid is sucked into the impeller, being formed into a straight portion, and each of the vanes has a positive vane angle with respect to a fluid advancing direction in the straight portion. With the above construction, a once-through pump can be obtained which is able to improve the air-blowing efficiency, reduce operation noise, and achieve a sufficient amount of blast or flow rate even within a limited design space.
In a preferred form of the first aspect of the present invention, the impeller comprises: a curvable wheel portion positioned at a side end face of an outer periphery of the impeller; and straight portion forming means for forming the straight portion in a part of the wheel portion; wherein the straight portion forming means comprises a guide plate member of a substantially D-shaped configuration disposed inside the wheel portion; and the wheel portion comprises a chain member which is slidable along an outer periphery of the guide plate member, the wheel portion being driven to rotate by means of a drive shaft which is in engagement with the chain member. With the above construction, a once-through pump can be obtained which is able to easily implement the impeller of the D-shaped configuration, reduce operation noise, and achieve a sufficient amount of blast or flow rate even within a limited design space.
According to a second aspect of the present invention, there is provided a once-through pump for accelerating fluid in a fluid passage, the pump comprising: an impeller provided in the flow passage and having an axis of rotation arranged in a diametrical direction of the flow passage; a vane array including a plurality of vanes provided on an outer periphery of the impeller; and a drive shaft for driving the impeller to rotate; wherein the impeller comprises: a belt-like connecting portion for connecting and arranging the respective vanes of the vane array with one another at substantially equal intervals; a single large wheel for supporting the belt-like connecting portion from its inside; and at least one small wheel disposed at a location in opposition to and apart from the large wheel for supporting the belt-like connecting portion from its inside; wherein the vane array arranged integrally with the belt-like connecting portion includes an arc-shaped centrifugal vane array and a linear vane array compulsorily formed by the large wheel and the at least one small wheel, and the small wheel forms the linear vane array at a suction side of the fluid with respect to the impeller, and the large wheel forms the centrifugal vane array at a discharge side of the fluid with respect to the impeller. With the above construction, a once-through pump can be obtained which is able to improve the pumping efficiency, reduce operation noise, and achieve a sufficient amount of pumping flow or flow rate even within a limited design space.
According to a preferred form of the second aspect of the present invention, the drive shaft together with the at least one small wheel forms the linear vane array, and the impeller has a substantially D-shaped cross sectional configuration. Thus, a once-through pump can be obtained which is able to reduce operation noise, and achieve a sufficient amount of pumping flow or flow rate even within a limited design space.
According to another preferred form of the second aspect of the present invention, the small wheel is formed integrally with the drive shaft to provide a pair of linear vane arrays with the small wheel arranged at their center, and the impeller has a cross sectional shape formed into a substantially spindle-shaped configuration. Thus, a once-through pump can be obtained which is able to simplify the pump construction, and achieve a sufficient amount of pumping flow or flow rate even within a limited design space.
According to a further preferred form of the second aspect of the present invention, the belt-like connecting portion has a plurality of outer periphery support sections arranged at equal intervals along a rotational direction of the impeller, and the respective vanes of the vane array are fixedly secured to the outer periphery support sections, and each arranged so as to maintain a constant vane angle. Thus, a once-through pump can be obtained which is able to provide stable pumping performance, and achieve a sufficient amount of pumping flow or flow rate even within a limited design space.
According to a still further preferred form of the second aspect of the present invention, the large wheel has a plurality of outer peripheral teeth arranged at equal intervals along a rotational direction of the large wheel, and the belt-like connecting portion has a plurality of inner peripheral teeth arranged at equal intervals in a rotational direction of the impeller so as to engage the outer peripheral teeth of the large wheel, and the outer peripheral teeth and the inner peripheral teeth are tuned to support dimensions of the cross sectional shape of the impeller at a plurality of locations including opposite axial ends of the impeller for preventing occurrence of distortion of the vanes at the opposite axial ends of the impeller. Thus, a once-through pump can be obtained which is able to avoid the generation of vibration, and achieve a sufficient amount of pumping flow or flow rate even within a limited design space.
According to a yet further preferred form of the second aspect of the present invention, the inner peripheral teeth of the belt-like connecting portion are formed integrally with the outer periphery support sections at a same pitch at which the outer periphery support sections are arranged. Thus, a once-through pump can be obtained which is able to improve precision in manufacturing the belt-like connecting portion, and achieve a sufficient amount of pumping flow or flow rate even within a limited design space.
According to a further preferred form of the second aspect of the present invention, each of the inner peripheral teeth of the belt-like connecting portion and the outer periphery support sections has a deformable quadrilateral cross sectional shape, and the outer peripheral teeth of the large wheel are formed into slant embossed shapes with respect to a rotational direction of the impeller and the large wheel, so that the quadrilateral cross sectional shape can be deformed in a direction to increase the vane angle of each of the vanes. Thus, a once-through pump can be obtained which is able to arbitrarily change the vane angle and improve the pumping performance.
According to a further preferred form of the second aspect of the present invention, the large wheel is formed integrally with the drive shaft. Thus, a once-through pump can be obtained which is able to change the vane angle in a centrifugal vane array in a reliable manner.
The above and other objects, features and advantages of the present invention will become more readily apparent to those skilled in the art from the following detailed description of preferred embodiments of the present invention taken in conjunction with the accompanying drawings.